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Apple dashes hopes for ZFS support in Snow Leopard

It appears that Apple made a last-minute decision to remove support for the …

Apple seems to have dashed the hopes of those hoping to be able to use high-performace ZFS storage pools and RAIDs with Mac OS X Snow Leopard Server. Apple has purged all references to the advanced filesystem from its website, conflicting with the rumor that full read and write support for ZFS was coming to Apple's server OS. It also appears that basic read-only support, currently in both the client and server versions of Leopard, may have been cut as well.

Up until Monday's WWDC keynote, the preview page for Snow Leopard Server specifically referred to ZFS support as one of its key features. "For business-critical server deployments, Snow Leopard Server adds read and write support for the high-performance, 128-bit ZFS file system, which includes advanced features such as storage pooling, data redundancy, automatic error correction, dynamic volume expansion, and snapshots," bragged the copy on Apple's website.

However, none of the current information about Snow Leopard includes any reference to ZFS. In fact, even a reference to read-only ZFS support that's currently in Leopard (both client and server) has been removed. Apple did not respond to our request for clarification on the matter.

The removal has lead to rampant speculation about the future of ZFS support for Mac OS X. Some hypothesize that it may be related to the recent purchase of Sun by database heavyweight Oracle, which is more invested in supporting BTRFS, while others suggest Apple may be planning to implement its own ZFS-like replacement. Given that Apple has been involved in porting ZFS to Mac OS X for at least three years, and that ZFS is still an active—if languishing—project on MacOSForge, neither of those explanations seems entirely likely.

However, one commenter in our Macintoshian Achaia, who appears to be familiar with developer builds of Mac OS X, suggests that support for ZFS was removed as far back as March of this year. The implementation from earlier this year was said to still have a number of bugs, and it didn't support recently added features such as booting capability. It seems more likely that Apple deemed this support not ready for release and pulled it from launch. That doesn't preclude ZFS support from being added into a point release sometime in the future, or even being pushed back to 10.7.

Since many capabilities of ZFS are so unlike those of the device-centric filesystems that came before it, many of the assumptions about filesystems that were used in the design of the Finder likely require some serious under-the-hood changes to integrate seamlessly. That is unfortunate for those hoping to harness the power and data reliability of ZFS in Snow Leopard. But if support is going to be included, I think we would all prefer that support to be as rock solid as possible.